We present the ASCA results of spatially resolved X-ray spectra of the Virgo cluster of galaxies. The northwest and south regions of the Virgo cluster of galaxies have been extensively investigated from ASCA, with the total exposure time and the covered area ~500 ksec and ~ 10 deg2, respectively. Based on the imaging and spectroscopic capability of ASCA, we excluded the contaminating sources other than the ICM, and successfully derived the temperature distribution in the Virgo cluster.
The temperature of the intracluster medium (ICM) in the south region of M87 are generally higher than those in the northwest region, and exhibit significant variation from position to position. We performed detailed analysis for the data in the linking region between M87 and M49 along the X-ray ``bridge'', and discovered a remarkable hot region. This region has an angular extent of ~4 x 103 arcmin2 and a temperature of kT = 4.38 keV, significantly hotter than the surrounding temperature of ~2 keV.
The observed features indicate that the hot region occupies a small angular size compared with the whole extent of the Virgo cluster, and it is surrounded by a cool gas of about 2 keV. The X-ray luminosity of the hot component is about 4 x 1041 erg s-1 in 2-10 keV. Based on the spectrum and emission measure of the hot component, its internal thermal energy is estimated to be ~1060 ergs and the gas density is ~10-4 cm-3. However, we could not distinguish the spectrum to be either thermal bremsstrahlung or non-thermal (power-law) from the fitting. It is possible to explain that the `hot' component is produced by inverse Compton scattering of the cosmic microwave background by relativistic electrons with gamma ~ 2000. Another possibility of an origin of the hard emission is non-thermal bremsstrahlung due to suprathermal electrons with energies grater than several keV. The total amount of the non-thermal electron in the region is estimated as ~9.0 x 1068. In either thermal or non-thermal case, the presence of the hot component strongly suggests that the shock is created in this region probably due to the motion of the gas associated with M49, approaching M87 with a velocity of >1000 km s-1.